Epidemiological investigation of fowl adenovirus infections in poultry in China during 2015–2018

Fowl adenoviruses (FAdVs) are associated with many diseases, resulting in huge economic losses to the poultry industry worldwide. Since 2015, outbreaks of FAdV infections with high mortality rates have been reported in China. A continued surveillance of FAdVs contributes to understand the epidemiology of the viruses. We isolated 155 FAdV strains from diseased chickens from poultry in China between 2015 and 2018. PCR analysis determined that 123 samples were FAdV species C, 27 were FAdV species E, and five contained two different FAdV strains. The phylogenetic analysis demonstrates that these sequences of hexon regions were clustered into three distinct serotypes: FAdV-4 (79.4%, 123/155), FAdV-8a (13.5%, 21/155) and FAdV-8b (3.9%, 6/155), of which FAdV-4 was the dominant serotype in China. The characterization of newly prevalent FAdV strains provides valuable information for the development of an effective control strategy for FAdV infections in chickens.